Changes in macular parameters in different types of amblyopia: optical coherence tomography study

Retinal and choroidal microvasculature and structural analysis in OCTA for refractive amblyopia diagnosis using machine learning

OBJECTIVE

To evaluate the features of retinal and choroidal microcirculation and structure in patients with amblyopia compared to healthy adolescents of the same age (>10 years old). To classify and diagnose amblyopia using machine learning techniques on optical coherence tomographic angiography (OCTA) images.

METHODS

Nineteen adolescents aged 11-17 with hyperopic refractive amblyopia and 22 age-matched healthy controls underwent 12 × 12 mm macular OCTA scans. The eyes were classified into three groups: amblyopic, contralateral non-amblyopic, and control. Retinal thickness (RT), choroidal thickness (ChT), and perfusion densities in the superficial capillary plexus (SCP) and deep capillary plexus (DCP) were measured across nine regions. A combination of statistical analysis and machine learning, including cross-validation and Random Forest classification, was used to enhance the diagnostic accuracy and classify amblyopic and normal eyes.

RESULTS

Retinal thickness was significantly higher in the amblyopic eyes compared to the control group in multiple regions, including the central (p < 0.001), nasal (p < 0.01), and temporal zones(p < 0.01). Choroidal thickness was also greater in the amblyopic eyes, particularly in the central and nasal regions (p < 0.05). However, no significant differences were observed in the perfusion densities of SCP and DCP. The machine learning classification model incorporating cross-validation achieved an accuracy of 92%, with Random Forest demonstrating improved classification and feature importance analysis.

CONCLUSION

The results indicate that eyes with refractive amblyopia have notably thicker retinal and choroidal layers, particularly in the central and nasal regions. Combining OCTA data with machine learning creates a strong diagnostic framework for detecting changes in the retina and choroid associated with refractive amblyopia. Utilizing sophisticated classification methods, like Random Forest and cross-validation, improves diagnostic precision and presents new possibilities for automated clinical evaluation.

Evaluation of optical coherence tomography changes in amblyopia

AIM

To study the Central Macular Thickness (CMT) and Retinal nerve fiber layer (RNFL) thickness (RNFLT) using Optical Coherence Tomography (OCT) in cases of amblyopia.

METHODS AND MATERIAL

The study was conducted on 30 patients of unilateral amblyopia having vision of less than 6/12 (30 amblyopic eyes and 30 fellow eyes) and age matched 30 eyes of normal controls aged between 5-30 years. Vision, Refraction and ophthalmological examination was done. OCT changes in macula and RNFL layer were evaluated in both eyes of each patient and controls. The data was statistically analyzed using SPSS version 22.

RESULTS

Out of 30 patients 14 were anisomyopic and 16 were anisohyperopics. The mean central macular thickness among amblyopic eyes was significantly increased (238.77±3.64 µm) a.c.t fellow eyes (218.73±4.71µm). Average retinal nerve fibre layer thickness among amblyopic eyes was significantly increased (100.50±7.70 µm) a.c.t fellow eyes (95.67±6.38) (P<0.001).

CONCLUSIONS

The eyes with unilateral anisometropic amblyopia were associated with higher Central Macular Thickness (CMT) and thicker global Retinal Nerve Fibre Layer (RNFL) when compared to normal fellow eyes.

Optical coherence tomography (OCT) parameters in amblyopia

BACKGROUND

Publications on optical coherence tomography (OCT) parameters in amblyopic eyes compared to fellow eyes are discordant. Our study not only compares OCT data of fellow and amblyopic eyes, but is the first study to deliver pilot results on OCT parameter changes after long-term electronic monitoring of occlusion therapy.

METHODS

Thirty eyes with strabismic, anisometropic or mixed amblyopia and the corresponding fellow eyes underwent OCT of the macula and optic disc with a Topcon 3D-OCT-2000. In a subgroup of six patients, the same examinations were additionally performed at the end of long-term objectively measured occlusion therapy with Occlusion-Dose-Monitoring (ODM) of ≥2135 hours. Paired t-tests or matched pairs Wilcoxon tests were performed to compare optic disc values, macular thickness, as well as thickness of different layers of the macula of the amblyopic eye versus the fellow eye. Specifically, the Ganglion Cell Layer (GCL) with the Inner Plexiform Layer (IPL) designated as GCL+, as well as combined with the Retinal Nerve Fiber Layer (RNFL) designated as GCL++, were analyzed. For the subgroup of patients with follow-up OCT, the same tests were performed to compare the values in both eyes before and after occlusion therapy.

RESULTS

Average thickness (AT) and total volume (TV) of the macula of amblyopic eyes (282.0 ± 13.0 µm; 7.98 mm3 ±0.37) were increased (marginally significant p=0.0495 for both) compared to fellow eyes (278.6 µm ± 13.3; 7.88 mm3 ±0.37), all other parameters did not differ. In the group with follow-up OCT, the AT and TV of the amblyopic eyes significantly decreased after occlusion (278.8 µm before vs. 268.3 µm after and 7.89 mm3 before vs. 7.59 mm3 after; p = .031 for both). The thicknesses of inner retinal layers were not significantly different between amblyopic and fellow eyes or after therapy.

CONCLUSIONS

Our results suggest that the macula of amblyopic eyes may be thicker than in fellow eyes, particularly in eyes with moderate-to-severe amblyopia. Occlusion therapy may lead to a thinning of the macula in the amblyopic eye or both eyes. The layers included in GCL+ and GCL++ do not seem to be the substrate of the observed structural changes.

Visual electrophysiological assessment of children with poor response to treatment for functional amblyopia

AIM

To assess the visual electrophysiological outcomes in children with functional amblyopia who exhibited poor response to conventional treatment.

METHODS

Twenty-one children with functional amblyopia, aged 5.7±2.1y (range: 4-10y), underwent comprehensive ophthalmic and refractive evaluations. Spectral domain-optical coherence tomography (SD-OCT) and multifocal electroretinography (mfERG) were conducted to analyze the macular retinal thickness and the first-order response P1 ring of the mfERG in the amblyopic eye (AE) compared to the fellow good eye (GE).

RESULTS

Initially, visual acuity in the AE ranged from 20/800 to 20/40, while the GE exhibited a range of 20/25 to 20/20 (P<0.01). After 6mo of treatment, 17 patients demonstrated improved visual acuity in the AE to 20/50 or better, while 4 children showed no improvement. SD-OCT revealed comparable macular and optic disc structures between the AE and GE. Prior to treatment, the mfERG P1 ring amplitude was significantly reduced in the AE compared to GE (P<0.05). The AE/GE ratio of P1 ring amplitude showed significant improvement post-treatment. However, a smaller AE/GE ratio before treatment was associated with poorer improvement post-treatment.

CONCLUSION

In the management of functional amblyopia, a thorough assessment of amblyopic eye examinations is crucial. Approximately 20% of amblyopic eyes may not achieve significant improvement in visual acuity, despite the absence of detectable organic retinal abnormalities. mfERG may reveal underlying abnormalities. Integrating mfERG into initial assessments or treatment follow-ups can aid in identifying potential hidden retinal defects and predicting the prognosis of the amblyopic eye.

Differences Between Amblyopic and Fellow Eyes in Optical Coherence Tomography: A Cohort from Jordanian Population

Background and Objectives: Amblyopia is a condition where children undergo unilateral or bilateral vision loss due to a variety of disorders that impact the visual pathway. The assessment of retinal nerve fiber layer (RNFL) thickness in amblyopia has made optical coherence tomography (OCT) a useful technique for studying the pathophysiology of this condition. This study was conducted to assess OCT results for various forms of amblyopia, including macular thickness and peripapillary RNFL thickness. It is the first of its kind in Jordan. Materials and Methods: Sixty-one individuals, aged 14 to 67, who had been diagnosed with unilateral amblyopia participated in a prospective study. Both eyes underwent spectral-domain OCT imaging, and clinical and demographic information was gathered. Relationships between different types of amblyopia and OCT measurements were investigated. Results: Compared to the contralateral fellow eyes, the amblyopic eyes showed thicker fovea, and there were differences in foveal and macular thickness observed between the sexes. Individuals with anisometropic amblyopia exhibited a greater central macular thickness. While nasal optic nerve thickness was adversely correlated with age, inferior optic nerve thickness was considerably lower in amblyopia. Conclusions: This research indicates unique OCT traits in amblyopic eyes, which may have a role in amblyopia diagnosis and treatment. The prevention of long-term visual impairment depends heavily on early detection and care. More studies using larger cohorts and longitudinal designs are necessary to improve our knowledge of the pathogenesis of amblyopia and to provide the best possible clinical management approaches.

Evaluation of Macular Pigment Optical Density in Eyes with Hyperopic Anisometropic Amblyopia Using Fundus Reflectometry

Objectives

This study aimed to evaluate the macular pigment optical density (MPOD) scores in eyes with hyperopic anisometropic amblyopia and compare those with their fellow and control eyes using one-wavelength fundus reflectometry.

Methods

This cross-sectional study enrolled 33 patients diagnosed with hyperopic anisometropic amblyopia aged 12-40 years. The control group consisted of 36 hyperopic and 42 emmetropic children, age-matched to the patients. Central macular thickness (CMT), MPOD, axial length (AL), best-corrected visual acuity, and refraction errors were measured between the study group and the control group.

Results

Eyes with the diagnosis of hyperopic anisometropic amblyopia had significantly higher mean and maximum (max) MPOD scores compared with their fellow eyes as well as hyperopic and emmetropic eyes (p<0.001 for all). The mean AL in eyes with hyperopic anisometropic amblyopia was statistically shorter than that in hyperopic and emmetropic controls (p=0.027, p<0.001, respectively). The mean CMT was found to be thicker in eyes with hyperopic anisometropic amblyopia when compared to their fellow eyes, as well as hyperopic and emmetropic controls, eventhough there was no significant difference was found among the four groups (p=0.052). The mean MPOD levels were significantly correlated with the difference in CMT (r=-0.21, p=0.032), and logMAR visual acuity scores (r=-0.44, p<0.001) in the hyperopic anisometropic amblyopia group.

Conclusion

The present study indicates that the MPOD is reduced in eyes with hyperopic anisometropic amblyopia. This reduction may be due to less visual stimulus-induced deterioration of foveal development and microarchitecture in anisometropic amblyopic eyes.

Evaluation of retinal microcirculation alterations using OCTA in hyperopic ametropic amblyopia patients before and after treatment

PURPOSE

We aimed to compare retinal microcirculation in hyperopic ametropic amblyopia patients before and after treatment and in healthy children using optical coherence tomography angiography (OCTA), and to explore the pathogenesis of hyperopic ametropic amblyopia.

METHODS

Eighteen patients with hyperopic ametropic amblyopia aged 4-8 years were selected as the patient group, and 18 age-matched healthy children were randomly selected as controls. The foveal avascular zone (FAZ) area, perimeter and circularity, vessel density (VD) and perfusion density (PD) of macular superficial retinal capillary plexus, macular thickness, peripapillary retinal nerve fiber layer thickness, and ganglion cell-inner plexiform layer thickness were compared between both groups. After 6 months of amblyopia treatment, the same parameters were measured again.

RESULTS

The VD and PD in the central, inner, inner nasal, and inner inferior regions in hyperopic ametropic amblyopia were lower than in the control group after adjustment for axial length. After 6 months of treatment, the VD increased significantly, except in the outer nasal and outer inferior regions. The PD in the central (p < 0.001), inner superior (p = 0.001), inner inferior (p = 0.011) and inner temporal (p = 0.026) regions increased. The FAZ perimeter and circularity significantly differed between the groups. After 6 months of treatment, the FAZ area and perimeter decreased, but circularity increased.

CONCLUSION

Hyperopic ametropic amblyopia eyes showed a significant decrease in vessel and perfusion densities. After amblyopia treatment, the vessel and perfusion densities of patients with hyperopic ametropic amblyopia increased, suggesting that abnormalities in the microvascular system are a pathogenic factor of amblyopia.

Optical coherence tomography predictors of the outcomes of occlusion therapy in anisometropic amblyopia

AIM

(1) To compare optical coherence tomography (OCT) parameters between amblyopic eyes and fellow eyes in patients presenting with anisometropic amblyopia. (2) To find OCT factors predicting the outcomes of occlusion therapy.

MATERIALS AND METHODS

This prospective study was conducted in a tertiary eye care center for a period of 20 months. Fifty-four children diagnosed with anisometropic amblyopic were included in the study. After complete ophthalmic and OCT examination, patients were advised to undergo occlusion therapy with large spectacle patch. Patients were reviewed after 6 months to record improvement in visual acuity and analyze their OCT parameters. Statistical tests used were paired "t" test and independent "t" test.

RESULTS

The mean age of 54 study patients was 9.24 ± 2.82 years. For comparison of OCT parameters, they were classified as myopic (22 patients), hypermetropic (24 patients), and astigmatic (8 patients) groups. In the anisomyopic amblyopia group, the mean inner macular thickness was significantly increased in fellow eyes (304.09 ± 11.06 μm) compared to amblyopic eyes (297.59 ± 14.16 μm). In the anisohyperopic amblyopia group, the outer macular thickness significantly increased in amblyopic eyes (286.43 ± 18.63 μm) when compared to fellow eyes (272.62 ± 14.90 μm). In the follow-up visit, 28 patients showed improvement and 6 patients did not show improvement in final best-corrected visual acuity, and the OCT parameters in amblyopic eyes of these two groups did not differ significantly.

CONCLUSION

Abnormal experience in early life does not affect the maturation process of retinal layers as evident by OCT parameters, and these parameters cannot predict the outcomes of occlusion therapy.

Evaluation of retinal microcirculation alterations using optical coherence tomography angiography in patients with hyperopia ametropic amblyopia: A case-control study

Given that there are controversial findings regarding vessel density in amblyopia, we quantified retinal microcirculation using optical coherence tomography angiography and compared it between hyperopic ametropic amblyopia eyes and age-matched control eyes. This case-control study was conducted from March 2021 to March 2022 at the Affiliated Eye Hospital of Nanchang University, Nanchang, China. Both groups included 72 eyes. Foveal avascular zone area, circularity and perimeter, perfusion density and vessel density of macular superficial retinal capillary plexus, macular thickness, macular volume, peripapillary retinal nerve fiber layer thickness, and ganglion cell-inner plexiform layer thickness were compared between hyperopia ametropic amblyopia eyes and age-matched control eyes. Additionally, best-corrected visual acuity, maximum corneal curvature, minimum corneal curvature, and anterior chamber depth were measured. In the hyperopia ametropic amblyopia eyes and control eyes, vessel density was 7.51 ± 2.13 and 9.91 ± 2.71 mm-1 in the central, 17.20 ± 1.38 and 18.25 ± 1.37 mm-1 in the inner, and 17.90 ± 0.88 and 18.43 ± 0.97 mm-1 in the full regions, respectively. The perfusion densities were 0.17 ± 0.06 and 0.23 ± 0.07 in the central, 0.41 ± 0.05 and 0.44 ± 0.03 in the inner, and 0.44 ± 0.03 and 0.46 ± 0.02 in the full regions, respectively. The central macular thicknesses of hyperopia ametropic amblyopia and control eyes were 240.04 ± 20.11 and 235.08 ± 24.41 µm, respectively. Foveal avascular zone perimeter and circularity (P < .043 and P = .001) significantly differed between the 2 groups. Hyperopia ametropic amblyopia eyes showed lower appreciably in vessel and perfusion densities, which could be one of the major pathophysiological mechanisms of hyperopia ametropic amblyopia and provide a new direction for the diagnosis and treatment of amblyopia.

[Role of optical coherence tomography in unilateral amblyopia]

PURPOSE

To compare the macular and papillary parameters on optical coherence tomography (OCT) between the amblyopic eye and the healthy eye in subjects with unilateral strabismic or anisometropic amblyopia.

PATIENTS AND METHODS

This is a cross-sectional and comparative study carried out over two years, from April 1, 2019, to March 31, 2021. We included patients aged over 5years, followed for unilateral amblyopia, free of any neurological and/or ocular pathology. The evaluation of the macular and papillary parameters in the amblyopic and healthy eyes was performed with Swept-Source Optical Coherence Tomography (OCT-SS). The parameters were compared according to age group and type of amblyopia.

RESULTS

We collected 50 patients, 29 children, and 21 adults, with a mean age of 19.8years. Amblyopia was secondary to anisometropia in 40 patients and strabismus in 10 patients. Analysis of macular tomographic parameters found no significant difference between amblyopic eyes and healthy eyes for mean macular thickness (P=0.86), central macular thickness (P=0.86), or mean macular volume (P=0.54). The mean retinal peripapillary fiber thickness (RNFL) was 107.48μm in the amblyopic eye and 103.8μm in the healthy eye, with a statistically significant difference (P<0.001). This significant thickening of the RNFL in amblyopic eyes was present in adults (P<0.001), children (P<0.001), anisometropic (P<0.001), and strabismic amblyopia (P=0.024). Analysis of the other optic nerve head parameters revealed no significant difference between amblyopic eyes and healthy eyes in terms of optic disc surface area (P=0.89), neuro-retinal annulus surface area (P=0.47), vertical (P=0.98) or horizontal (P=0.74) cup to disc ratio.

CONCLUSION

Amblyopia is accompanied by thickening of the peripapillary retinal fibers without macular repercussions. However, larger prospective studies are needed to confirm these results.

Long-term effects of early/late-onset visual deprivation on macular and retinal nerve fibers layer structure: A pilot study

BACKGROUND/AIMS

Tomographic analysis of macular and peripapillary retinal nerve fibers layer (RNFL) thickness in patients with history of congenital (CC) and developmental cataract (DC).

METHODS

Analysis of macular and RNFL thickness using a spectral-domain optical coherence tomography was performed. Retinal layers thickness was measured using the internal segmentation software. Measurements of affected (unilateral and bilateral), contralateral eyes and control eyes were compared.

RESULTS

Patients with history of CC or DC (n = 13 and 11 respectively) and 35 healthy control subjects were enrolled. Thicker inner and outer nuclear layers (INL, ONL) and thicker ONL were found when CC and DC group when compared to controls respectively. Bilateral CC showed the most relevant differences. Slight thickening of CC inner retinal layers were found when compared to DC. Increased superonasal RNFL thickness was found in CC group when compared to DC and controls. Thickening of RNFL of contralateral unaffected eyes of unilateral CC were found when compared to controls.

CONCLUSION

Significant macular and RNFL thickness changes between CC, DC patients and controls that partially involve also contralateral unaffected eyes of unilateral congenital cataract were found. CC and DC groups show significant differences only in inner retinal layers thickness. Our data suggest that early visual deprivation may influence retinal arrangements occurring during development involving predominantly the outer nuclear layer and para/perifoveal inner retinal layers, and confirm that early treatment of CC allow to achieve better long-term visual outcome. Moreover functional and structural data support the hypothesis that unilateral amblyopia is not exclusively an unilateral issue.

Retinal nerve fiber layer thickness in amblyopia

Purpose

To report retinal nerve fiber layer thickness (RNFLT) in eyes with amblyopia compared with contralateral healthy eyes.

Methods

In this cross-sectional study, we included patients with anisometropic amblyopia, strabismic amblyopia, and mixed amblyopia. All subjects underwent complete ophthalmic examination, including RNFLT measurement with time-domain OCT (Stratus OCT) and scanning laser polarimeter (GDX VCC). A paired "t" test was used to compare average and quadrant-wise RNFL thickness between the amblyopic and contralateral normal eyes. In addition, an analysis of variance test was used to compare various RNFL thickness parameters between the three groups.

Results

A total of 33 eyes of 33 subjects with anisometropic amblyopia, 20 eyes of 20 subjects with strabismic amblyopia, and 38 eyes of 38 subjects with mixed amblyopia were included. In the anisometropic amblyopia group, the average RNFLT in the amblyopic eye was 98.2 μm and 99.8 μm in the fellow normal eye (P = 0.5), the total foveal thickness was 152.82 μm (26.78) in the anisometropic eye and 150.42 μm (23.84) in the fellow eye (P = 0.38). The difference between amblyopic and contralateral normal eye for RNFL and macular parameters was statistically insignificant in all three groups. The RNFL thickness in four quadrants was similar in the amblyopic and non-amblyopic eye between all three groups and statistically non-significant.

Conclusion

Our study showed that RNFL thickness was similar in amblyopic and non-amblyopic eyes between all three amblyopia groups.

[Correlation of chorioretinal parameters with anatomical, optical and functional indicators of eyes with amblyopia of various origins]

Purpose. To measure thickness of the central retina and choroid, retinal nerve fiber layer and ganglion cell complex in the macular region, retinal nerve fiber layer in the peripapillary region in eyes with various types of amblyopia, and to analyze its relationship with best corrected visual acuity, refraction and axial eye length.

MATERIAL AND METHODS

The study included 50 patients aged 5 to 16 years (mean age 10.04±3.01 years). All patients were divided into 6 groups: 1 - relative amblyopia with congenital myopia (23 eyes); 2 - dysbinocular amblyopia (14 eyes); 3 - refractive amblyopia (16 eyes); 4 - anisometropic amblyopia (7 eyes); 5 - paired eyes of patients with amblyopia (20 eyes); 6 - control group (20 eyes). Chorioretinal parameters were determined using the RS-3000 Advance 2 spectral optical coherence tomography system («Nidek», Japan). Correlation analysis was performed using the Pearson's linear correlation coefficient (r). The level of significance of the differences was determined by the standard Student's t-test.

RESULTS

Morphological changes in the sensory and choroid membranes of the eye were revealed in groups with amblyopia of various origins compared to the control group, as well as in the fellow eyes. Intergroup comparison showed the presence of more significant disorders in refractive and relative amblyopia due to congenital myopia. Correlation analysis showed that structural changes in the posterior pole are more related to the anatomical and optical parameters of the eyes.

CONCLUSION

Optical coherence tomography allows detection of microscopic structural anomalies in the posterior pole of the eye in amblyopia of various origins, assists in differential diagnosis of this condition with organic pathology, and - most importantly - helps peer deeper into the pathogenesis of this disease.

Evaluation of macular and optic nerve head parameters in amblyopic eyes: An optical coherence tomography study

PURPOSE

To evaluate morphological differences in retinal nerve fibers layers (RNFL), optic nerve head (ONH), ganglion cell complex (GCC), and macular thickness between amblyopic and normal eyes from spectral domain optical coherence tomography (SD-OCT).

METHODS

Of 234 eyes of 117 children, four groups emerged: group A (162 eyes of 81 non-amblyopic subjects); group B (32 fellow eyes of 32 subjects with monolateral amblyopia); group C (32 amblyopic eyes of 32 subjects affected by monolateral amblyopia); group D (8 amblyopic eyes of 4 subjects with bilateral amblyopia). Patients underwent SD-OCT for ONH parameters, RNFL, GCC and macular thickness, retina map, and ONH scan quality index (SQI). Two-sided p values <0.05 were taken as statistically significant. (Analysis: STATA v.13).

RESULTS

Parameters with a significant difference between groups (p < 0.005) with their Standard Deviation (SD) are presented: rim area, 2.08 (0.49) mm² in group A and 1.76 (0.68) mm² in group C; disk area, 2.43 (0.45) mm² in group A and 2.02 (0.71) mm² in group C; central macular thickness, 250.99 (19.74) µm in group A and 267.16 (23.52) µm in group C; nerve fiber ONH SQI, 62.82 (13.15) in group A, 51.26 (15.55) in group C, 48.29 (14.37) in group D; retina map SQI, 63.34 (10.34) in group A and 57.34 (9.84) in group C. For other parameters no significant difference was observed (p > 0.005).

CONCLUSIONS

Amblyopia may influence optic nerve morphology, central macular thickness, and OCT scan quality. RNFL and GCC are not affected by monolateral amblyopia.

Reduced Photoreceptor Outer Segment Layer Thickness and Association with Vision in Amblyopic Children and Adolescents with Unilateral High Myopia

PURPOSE

To quantitatively compare reflectivity and other morphological changes of the photoreceptors of normal eyes with amblyopic eyes using the longitudinal reflectance profile (LRP) on swept-source optical coherence tomography (SS-OCT) images in children and adolescents with unilateral high myopia. The relationships between OCT parameters and visual acuity were investigated.

METHOD

Twenty-six amblyopes with unilateral high myopia and 34 age-, axial length- and spherical equivalent-matched normal controls were recruited. All participants underwent SS-OCT and detailed ophthalmic investigations. The reflectivity of the outer retinal and photoreceptor outer segment layer thickness were quantified by LRP using ImageJ software. All parameters were measured at three selected regions: at the fovea, 1 mm nasal to the fovea and 1 mm temporal to the fovea. Differences between the groups were evaluated.

RESULTS

The mean choroidal thickness was thinner in amblyopic eyes compared with controls (165.19 ± 59.02 μm vs 214.97 ± 66.41 μm at the fovea; 128.77 ± 57.06 μm vs 161.54 ± 57.37 μm at 1 mm nasal to the fovea; 188.13 ± 59.51 μm vs 219.87 ± 61.78 μm at 1 mm temporal to the fovea, P < .05). The amblyopic eyes had higher reflectivity of the ellipsoid zone at 1 mm nasal to the fovea only (85.41 ± 25.78 vs 70.76 ± 18.69, P = .02). The mean length of the photoreceptor outer segment (OS) layer was significantly greater in the control eyes than in the amblyopic eyes at all three regions (20.19 ± 1.89 vs 18.70 ± 2.23 at the fovea, P = .006; 16.06 ± 1.47 vs 15.07 ± 1.30 at 1 mm nasal to the fovea, P = .008; 15.81 ± 1.58 vs 14.56 ± 1.87 at 1 mm temporal to the fovea, P = .006). The shortened OS length was associated with poorer visual acuity.

CONCLUSION

The results of this study revealed that the amblyopes with unilateral high myopia had thinner choroidal thickness and shortened OS thickness compared to normal controls. The findings indicate that abnormal anatomic changes in the amblyopic children and adolescents with unilateral high myopia were not only due to high myopia but more likely due to a combination of high myopia and amblyopia.

Changes in macular ultrastructural morphology in unilateral anisometropic amblyopia

It is controversial that retina and photoreceptors are involved in amblyopic development. Lack of imaging devices for quantitative assessment of photoreceptors in vivo impedes further investigation. In this study we investigated the differences of macular thickness, outer nuclear layer (ONL) thickness and cone density among eyes with unilateral anisometropic amblyopia, amblyopic fellow eyes, and normal control eyes using high-definition spectral-domain optical coherence tomography and adaptive optics imaging system. Thicker fovea and parafovea with characteristic quantitative retinal changes in unilateral amblyopic patients indicated that the amblyopic process might involve the retina. Cones tended to be homogeneously distributed at 1.5° from the foveal center in all participants. However, we did not detect any significant differences in cone density and ONL thickness at 1.5° from the foveal center in patients with unilateral amblyopia when compared with the fellow eyes and the normal control eyes. This is the first study to explore whether photoreceptors are involved in amblyopic development in vivo that would help for understanding the underlying mechanisms of amblyopia. Whether macular changes relate to cone photoreceptors migration of the amblyopic eyes remains to be determined.

Analysis of macular, foveal, and retinal nerve fiber layer thickness in children with unilateral anisometropic amblyopia and their changes following occlusion therapy

Purpose:

To analyze macular thickness (MT), foveal thickness (FT), and retinal nerve fibre layer thickness (RNFLT) in children with unilateral anisometropic amblyopia and their changes following occlusion therapy.

Methods:

A prospective, longitudinal, and comparative study of 60 children aged between 5 and 18 years consisted of two groups, group 1: 30 children with unilateral anisometropic amblyopia; group 2: 30 normal children. Best corrected visual acuity (BCVA), a detailed ocular examination, spectral domain optical coherence tomography for MT, FT, and RNFLT in both eyes were done at visit one (baseline) and every 3 months for a year following occlusion therapy (initiated one month after first visit) in group 1.

Results:

Mean BCVA, MT, FT, and RNFLT in amblyopic eyes at first visit were 0.63 ± 0.405, 286.9 ± 6.522 μm, 195.90 ± 8.462 μm, and 100.87 ± 6.240 μm, respectively and at last visit after occlusion therapy were 0.50 ± 0.318, 248.9 ± 11.681 μm, 169.47 ± 10.941 μm, and 99.43 ± 5.722 μm, respectively. At first visit, mean BCVA, MT, FT, and RNFLT in nonamblyopic eyes (group 1) were 0 ± 0, 240 ± 10.447 μm, 159.27 ± 9.285 μm, 98.63 ± 4.723 μm and in normal eyes (group 2: average of right and left eyes) were 0 ± 0, 239.8 ± 4.294 μm, 143.6 ± 4.61 μm, 100.5 ± 2.895 μm, respectively.

Conclusion:

MT and FT, which were more in amblyopic eyes as compared to normal fellow eyes and group 2, decreased with improvement in BCVA after occlusion therapy. However, there was no difference in RNFLT between amblyopic eyes and normal fellow eyes and group 2 before and after occlusion therapy.

Imaging Amblyopia: Insights from Optical Coherence Tomography (OCT)

Amblyopia refers to visual impairment resulting from perturbations in visual experience during visual development, typically secondary to strabismus, uncorrected refractive error, and/or deprivation. Amblyopia has traditionally been considered a cortical disease, but the depth of our understanding of this complex neurodevelopmental condition is limited by our ability to appreciate structural pathophysiology in the visual pathway. Recent advances in Optical Coherence Tomography (OCT) have facilitated numerous studies of the structural changes in the retina and optic nerve, thereby expanding our appreciation for the pathogenesis of this condition. In this review, we summarize findings from studies evaluating retinal, retinal nerve fiber layer, and choroidal thickness changes in patients with amblyopia. Focusing on the largest and most recent studies, we discuss common limitations and confounding variables in these studies. We summarize recent advances in ocular imaging technology and reconcile the findings of early histological reports with those of structural OCT in amblyopia.

Analysis of Macular Vessel Density and Foveal Avascular Zone Using Spectral-Domain Optical Coherence Tomography Angiography in Children With Amblyopia

PURPOSE

To quantify the foveal avascular zone and the whole, parafoveal, and foveal vessel density of superficial and deep capillary plexus in amblyopic eyes and age-matched controls and to compare the measurements.

METHODS

This cross-sectional study involved 49 eyes from 17 patients with amblyopia and 21 healthy children (aged 6 to 16 years). Optical coherence tomography angiography was performed for all participants and superficial capillary plexus, deep capillary plexus, and foveal avascular zone were evaluated. Data from amblyopic eyes, fellow eyes with unilateral amblyopia, and control eyes were compared using the Mann-Whitney U test.

RESULTS

The mean patient age was 8.6 ± 2.5 years in the amblyopia group and 9.6 ± 2.9 years in the control group. The mean foveal avascular zone measurements were 0.251 ± 0.1 mm² in the amblyopia group and 0.291 ± 0.1 mm² in the control group. The whole, foveal, and parafoveal vessel densities of superficial capillary plexus were 48.8% ± 3.7%, 23.8% ± 8.8%, and 50.9% ± 4.6% in the amblyopia group and 48.4% ± 2.5%, 19.3% ± 5.4%, and 51.3% ± 2.7% in the control group. The whole, foveal, and parafoveal vessel densities of deep capillary plexus were 51.8% ± 4.3%, 37.6% ± 5.8%, and 54.8% ± 4.2% in the amblyopia group and 54.4% ± 3.2%, 34.9% ± 7.4%, and 56.8% ± 3.2% in the control group. No statistically significant difference was detected in all measurements.

CONCLUSIONS

Assessment of the foveal avascular zone and vessel density of superficial capillary plexus and deep capillary plexus with optical coherence tomography angiography revealed no difference between amblyopic eyes, controls, and fellow eyes of patients with unilateral amblyopia. [J Pediatr Ophthalmol Strabismus. 2019;56(1):55-59.].

Lamina cribrosa thickness in children with hyperopic anisometropic amblyopia

AIM

To determine lamina cribrosa thickness (LCT) in the optic nerve head region of the eyes in children with hyperopic anisometropic amblyopia and to compare this thickness with that of fellow eyes, hyperopic non-amblyopia, and age-matched controls.

METHODS

Thirty-two patients (12.0±1.8y, mean± standard deviation) with hyperopic anisometropic amblyopia, 31 subjects with age- and refractive error-matched hyperopic non-amblyopia (10.7±2.2y), and 32 age-matched controls (11.2±2.0y) were included in this prospective, cross-sectional study. LCT was measured using an enhanced depth-imaging program of a spectral domain optical coherence tomographic instrument in all participants, and the correlation between LCT and axial length was calculated.

RESULTS

The mean LCT was 180.9±29.4 µm in amblyopic eyes, 247.7±19.0 µm in fellow eyes, 251.6±27.3 µm in hyperopic non-amblyopic eyes, and 240.2±15.8 µm in control eyes. Lamina cribrosa in amblyopic eyes was significantly thinner than fellow, hyperopic non-amblyopic, and control eyes (P<0.05). There was no significant correlation in LCT and axial length between amblyopic (P=0.16) and control (P=0.31) group.

CONCLUSION

Lamina cribrosa of eyes with hyperopic anisometropic amblyopia is significantly thinner than that of fellow eyes, hyperopic non-amblyopia, and age-matched controls. The LCT profile in amblyopic eyes is different from that observed in fellow, hyperopic non-amblyopic, and control eyes.

Evaluation of retinal structure in unilateral amblyopia using spectral domain optical coherence tomography

PURPOSE

To investigate potential differences in the retinal nerve fiber layer (RNFL) thickness, macular thickness and foveal thickness between amblyopic eyes and normal fellow eyes on spectral domain optical coherence tomography (SD-OCT).

METHODS

A cross-sectional study of patients ≥10 years of age with unilateral amblyopia resulting from an anisometropic, strabismic or deprivative cause. Comprehensive ophthalmic examination was completed and the retinal structures of both eyes were measured using SD-OCT. We compared the measurements obtained between the amblyopic eye and the fellow normal eye in each subject.

RESULTS

Twenty-six unilateral amblyopia patients with a mean age of 29.92 ± 14.19 years old participated in the study, of which 17 (65.4%) were classified as anisometropic, 7 (26.9%) as strabismic, and 2 (7.7%) as deprivative. For the amblyopic eye and fellow normal eye, respectively, the mean RNFL thickness was 95.87 ± 14.56 μm and 97.87 ± 14.56 μm (P = 0.628), the mean macular thickness was 270.87 ± 14.43 μm and 275.60 ± 14.43 μm (P = 0.251) and the mean foveal thickness was 250.59 ± 27.82 μm and 242.91 ± 27.82 μm (P = 0.332). SD-OCT assessments revealed no statistically significant differences between both eyes.

CONCLUSIONS

Using SD-OCT, there were no significant changes in the retinal structure of amblyopic eyes. Therefore, amblyopia does not seem to have a profound structural effect on the retinal nerve fiber layer, the macula, or the fovea.

Macular Thickness in Moderate to Severe Amblyopia

PURPOSE

To compare the macular retinal thickness of moderately to severely amblyopic eyes with non-amblyopic eyes as controls.

METHODS

This case control study was conducted on 56 children aged 4 to 10 years old (64.3% female subjects). Twenty-eight children had unilateral amblyopia (28 amblyopic eyes as cases and 28 normal fellow eyes as internal controls) and 28 children had normal visual acuity in both eyes and were considered as external controls (n = 56 eyes). Among our cases, 14 had strabismic amblyopia and 14 had anisometropic amblyopia. Macular retinal thickness was measured using optical coherence tomography at the center and in 1-, 3-, and 6-mm rings.

RESULTS

Best-corrected visual acuity of the amblyopic eyes was less than that of the internal and external controls, and the best-corrected visual acuity of their fellow eyes was also less than that of the external controls. Thickness of the central macula and a 1-mm ring area in the amblyopic eyes was higher than that of both internal and external controls. Difference of central macular thickness ≥20 μm between two eyes of the amblyopic children was significantly more than non-amblyopic subjects.

CONCLUSIONS

Based on the results of this study, the macular retinal thickness was significantly higher in moderate to severe amblyopic eyes compared to their fellow eyes and external controls. This might be due to macular developmental disorders in amblyopic eyes. Therefore, optical coherence tomography imaging is recommended if subtle macular abnormalities are suspected in moderate to severe amblyopic eyes.

OCT angiography findings in children with amblyopia

PURPOSE

To compare the microstructure and vascularity of amblyopic eyes in children with their contralateral eye and with eyes from control children using optical coherence tomography angiography (OCT-A).

METHODS

We conducted a prospective, cross-sectional evaluation of macular and optic disk vascular density and flow area using OCT-A (Avanti RTVue XR, Optovue Inc, Fremont, CA). Parameters were calculated using automated software.

RESULTS

A total of 52 children were included: 26 subjects with amblyopia and 26 nonamblyopic controls. The amblyopic eye of subjects showed a statistically significant decrease in macular vascular density (P = 0.0171) of the superficial capillary plexus (SCP), in the optic disk flow area (P = 0.0195) and in the average retinal nerve fiber layer thickness (P = 0.0194) as well as a marginally statistically significant decrease in the macular flow area of the SCP (P = 0.0305) and in the optic density (P = 0.0279). Compared with randomly selected eyes of controls, amblyopic eyes showed a statistically significant decrease in the macular flow area of the SCP (P = 0.005) and of the deep capillary plexus (DCP; P = 0.002), in the macula vascular density of the SCP (P = 0.022), in the optic disk flow area (P = 0.004), and a marginally statistical significant increase in the area of foveal avascular zone of the DCP (P = 0.038).

CONCLUSIONS

In our study cohort amblyopic eyes manifested significant differences in macular and optic disk vascularization. The clinical significance of these findings warrants further research.